1. Field of the Invention
The invention is related to the field of electronic engine controls and in particular to a closed loop electronic engine control which distributes the delivered quantity of fuel among the individual engine cylinders so as to equalize the contribution of each cylinder to the total output torque of the engine.
2. Prior Art
Fuel distribution engine control systems are known in the art. Schira et al. in U.S. Pat. No. 4,357,662 discloses a closed loop fuel distribution in which the fuel delivered to each cylinder is computed from the amplitude and phase angle of the individual torque impulses to the engine's crankshaft as a function of engine speed. In another type of fuel control system using engine roughness as the sensed parameter to close the loop, Bianchi et al. in U.S. Pat. No. 4,044,236 teaches measuring the rotational periods of the engine's crankshaft between two sequential revolutions of the engine. The differential is digitally measured in an updown counter counting at a frequency proportional to engine speed. In an alternate type of closed loop fuel control system, Frobenius et al. in U.S. Pat. No. 4,044,234 teaches measuring the rotational periods of two equal angular intervals, one before and one after the top dead center position of each piston. The change in the difference between the two rotational periods of the two equal angular intervals for the same cylinder is compared against a reference value and an error signal is generated when the change exceeds the reference value. Frobenius in U.S. Pat. No. 4,044,235 teaches an alternate roughness control system wherein the periods of three sequential revolutions are compared to determine engine smoothness.
In all of the above, the fuel control systems are closed loop and correct the quantity of fuel being supplied by the engine in a closed loop manner. However only Schira et al. disclosed a fuel control system capable of distributing the fuel among the individual engine cylinders to equalize the torque contribution of each cylinder to the total output torque of the engine. Disclosed herein is a closed loop fuel redistribution control system, in which the base quantity of fuel to be delivered to the individual cylinders is computed by a fuel control computer in response to the operational parameters of the engine and the computed base fuel quantities distributed to the individual engine cylinders in response to the differences in the detected torque impulses tending to equalize the contribution of each cylinder to the total output torque.